2026 ICD-10-CM Diagnosis Code K31.83Achlorhydria

ICD-10-CM Codes›K00–K95›K20-K31›K31

ICD-10-CM K31.83
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K31.83 is a billable ICD-10-CM diagnosis code for achlorhydria. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 391 through 392. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified disorders of stomach and duodenum.

Code Identity

ICD-10-CM Code
K31.83
Billable Status
Yes — Valid for Submission
Code Describes
Achlorhydria
Short Description
Achlorhydria
Same as the full description in the CMS dataset.
Parent Code
K31.8
Other specified diseases of stomach and duodenum

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK20-K31Diseases of esophagus, stomach and duodenum
CategoryK31Other diseases of stomach and duodenum
This CodeK31.83Achlorhydria

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Achlorhydria
  • Hypochlorhydria

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR DIG008
Other specified and unspecified disorders of stomach and duodenum
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Achlorhydria

    a lack of hydrochloric acid in gastric juice despite stimulation of gastric secretion.

Patient EducationClinical

Stomach Disorders

Your stomach is an organ between your esophagus and small intestine. It is where digestion of protein begins. The stomach has three tasks. It stores swallowed food. It mixes the food with stomach acids. Then it sends the mixture on to the small intestine.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert K31.83 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
536.0 Achlorhydria
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K31.83Overview

What is the ICD-10 code for achlorhydria?

The ICD-10-CM code for achlorhydria is K31.83 (sometimes written as K3183). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is K31.83 (Other specified diseases of stomach and duodenum) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report achlorhydria on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K31.83 group to?

When achlorhydria is the principal diagnosis on an inpatient stay, it groups to MS-DRG 391, 392, with relative weights from 0.7796 to 1.2683 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K31.83?

Under the General Equivalence Mappings, achlorhydria converts to ICD-9-CM 536.0 (achlorhydria). The mapping is a direct match.